JS and Images

Which of the following best defines: Class

• A blueprint or template that defines what an object looks like and what it can do.
• A specific thing created from a function that stores data
• A variable that holds multiple values in a list
• A loop that repeats until a condition is met

Answer explanation

A blueprint or template that defines what an object looks like and what it can do.

Which of the following best defines: Object

• A specific instance created from a class, with its own data and behaviors. In our program, image is an object.
• A blueprint used to define what variables will look like
• A function that belongs to a loop
• A keyword used to declare a new variable

Answer explanation

A specific instance created from a class, with its own data and behaviors. In our program, image is an object.

Which of the following best defines: Attributes (variables of an object)

• The actions an object can perform, like setting a color
• The loops used to process an object's data
• The data or characteristics that an object stores, such as its width, height, or pixel colors.
• The functions called to create a new object

Answer explanation

The data or characteristics that an object stores, such as its width, height, or pixel colors.

Which of the following best defines: Behaviors (methods or functions of an object)

• The variables that store an object's characteristics
• The actions an object can perform. For example, setRed() and getPixel() are behaviors of the image object.
• The conditions that determine when an object is created
• The keywords used to declare an object's data type

Answer explanation

The actions an object can perform. For example, setRed() and getPixel() are behaviors of the image object.

Which of the following best defines: Variable

• A block of code that runs only when called by name
• A named container used to store a value in a program. Its value can change as the program runs.
• A structure that repeats a set of instructions multiple times
• A keyword that creates a new function in JavaScript

Answer explanation

A named container used to store a value in a program. Its value can change as the program runs.

Which of the following best defines: The var keyword

• A symbol used to assign a value to an existing function
• A JavaScript keyword used to declare, or create, a new variable.
• A command that starts a new loop in JavaScript
• A built-in method used to get the value of a pixel

Answer explanation

A JavaScript keyword used to declare, or create, a new variable.

Which of the following best defines: Function

• A named, reusable block of code that performs a specific task. Only runs when called. Often written as a name followed by ().
• A structure that repeats a block of code until a condition is false
• A container that stores a list of values accessible by index
• A keyword used to declare a new variable in JavaScript

Answer explanation

A named, reusable block of code that performs a specific task. Only runs when called. Often written as a name followed by ().

Which of the following best defines: Loop

• A structure that repeats a block of code multiple times, usually until a condition is no longer true.
• A named block of code that runs once when called
• A container used to store and retrieve multiple values
• A method that belongs to an object and performs an action

Answer explanation

A structure that repeats a block of code multiple times, usually until a condition is no longer true.

Which of the following best defines: Nested loop

• A loop that calls a function every time it repeats
• A loop that runs only if a specific condition is true
• Two loops that run at the same time on different data
• A loop placed inside another loop. The inner loop completes all its repetitions each time the outer loop runs once.

Answer explanation

A loop placed inside another loop. The inner loop completes all its repetitions each time the outer loop runs once.

Which of the following best defines: Array

• A data structure that stores an ordered list of values, each accessible by an index number starting at 0.
• A variable that can only store one value at a time
• A function that returns the size of an image in pixels
• A loop that processes each item in a list one at a time

Answer explanation

A data structure that stores an ordered list of values, each accessible by an index number starting at 0.